Research on and development of magneto-optical disks as rewritable optical disks are progressing, and some magneto-optical disks have already been practically used as external memories for computers.
The magneto-optical disk uses a perpendicularly magnetized film as a recording medium, and records and reproduces information using light. The magneto-optical disk is characterized by having a large storage capacity compared with a floppy or hard disk including a film which exhibits in-plane magnetization.
In recent years, a memory having a larger capacity is demanded, and research on hard disks and magneto-optical disks is actively carried out to achieve an improved recording density.
Japanese Publication for Examined Patent Application No. 57859/1988 (Tokukosho 63-57859) proposes an optical recording and reproduction apparatus which achieves a high recording density by providing groove portions and land portions of widths arranged to be substantially 1 to 1 on a transparent substrate and by recording and reproducing information on guide tracks formed on the groove and land portions.
However, with the above-mentioned conventional structure, when the track density is increased and when reproducing information from a track on a groove portion (or land portion), the level of crosstalk caused by the tracks on the adjacent land portions (or groove portions) increases. This imposes a limitation in increasing the recording density.